The goals of the proposed work are to elucidate the protein-protein interactions and signal transduction pathways involved in the recruitment of GLuR2-containing receptors in response to high frequency stimulation to synapses that formerly lacked them. A combination of electrophysiology, biochemistry (peptide perfusion), pharmacology, and transgenic animals will be used. To dissect the roles of individual proteins in GluR2 regulation the interaction between the C-termini of the AMPA receptor subunits with intracellular proteins will be disrupted with the use of small peptides directed against the interaction sites on GluR1, 2, 3, and 4 subunits. Complementary to this approach will be to use transgenic animals that lack GluR2-interacting proteins (GRIP1/GRIP2 or PICK1) or that lack the last 7 amino acids of the C-terminus of GluR1, GluR2, GluR3, or GluR4. Next, the targets of Ca2+ influx through Ca2+- permeable AMPA receptors will be dissected with pharmacological manipulations of kinases and phosphatases. This project will potentially reveal the determinants of the distribution and regulation of AMPA receptor subunits in general, a process that contributes to the fundamental function of glutamatergic synapses throughout the nervous system.